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Thread: Help with HD44780 4x20 LCD

  1. #1
    Variable Bitrate Pokey's Avatar
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    Help with HD44780 4x20 LCD

    I need some help with getting the lcd pinouts to parallel rs232 pinouts. Im using schematics and code from "the ee compendium", and i belive something is wrong either the code or wiring.

    Can someone direct to another source of schematics and code for testing these HD44780 LCDs that i have. And any other docs that might help me.

    Thanks in advanced!
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  2. #2
    Low Bitrate vision's Avatar
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    HD44780-Based LCD Modules
    http://www.doc.ic.ac.uk/~ih/doc/lcd/

    How to control a HD44780-based Character-LCD
    http://home.iae.nl/users/pouweha/lcd/lcd.shtml

    Winamp OpenSource LCD Plugin for various LCD & VFD modules
    http://www.markuszehnder.ch/projects/lcdplugin/

    Setting up a 40x4 HD44780 compatible LCD module
    http://www.overclockers.com.au/~mwp/...44780-40x4.htm

    etc.

    google rulez

  3. #3
    Raw Wave Rob Withey's Avatar
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    Quote Originally Posted by Pokey
    I need some help with getting the lcd pinouts to parallel rs232 pinouts.
    Which is it, parallel, or rs232 (because rs232 is serial)?

    I don't know if 44780 supports a serial interface natively, it'll do 4 bit or 8 bit parallel interface without any additional support hardware.
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  4. #4
    Variable Bitrate Pokey's Avatar
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    I from the old school. i know its a RS232 connector (which 'use to be' used for serial only) but now computers are using that connector for parallel printer. In the Apple days, we use to have centronics for parallel, and rs232 for serial.

    This is the parallel printer out, a D25 female connector.

    Did this answer the question or make matters worst?
    Dual Lilliput's 70NP/C/T
    Syntax SV266AD KT266A
    AMD Athlon XP 2000
    Viking 256MB DDR
    D-Link Wireless 802.11B
    Seagate 120GB
    OrbitMicro 250W DC/DC converter
    SII Wireless Audio Link
    Digimoto OBD-II
    Earthmate GPS
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    D-Link Bluetooth

  5. #5
    Raw Wave Rob Withey's Avatar
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    Quote Originally Posted by Pokey
    I from the old school. i know its a RS232 connector (which 'use to be' used for serial only) but now computers are using that connector for parallel printer. In the Apple days, we use to have centronics for parallel, and rs232 for serial.

    This is the parallel printer out, a D25 female connector.

    Did this answer the question or make matters worst?
    I'm from the old skool too. It answered the question.

    Not meaning to be picky, but it sounds like you mean a 25pin d-type (or DB25), not an rs232 connector. D type connectors look like this:

    http://www.maplin.co.uk/products/mod...116&Products=7

    RS232 (which is a serial communication standard) defines the protocol and signal wires, not the shape (current PCs often have a DB9 RS232 port for example). 25pin d-type defines the shape of the connector. Centronics is yet another shape of connector (although it used to be synonymous with the protocol):

    http://www.maplin.co.uk/products/mod...328&Products=1

    I think vision probably answered your question suitably (especially the last link). There are absolutely tons of circuits out there for connecting 44780 displays to the parallel port.
    Old Systems retired due to new car
    New system at design/prototype stage on BeagleBoard.

  6. #6
    Variable Bitrate Pokey's Avatar
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    i just didnt know how to explain what i needed in a short description. I figured if i explained it all out, it would of been to long and probably confused alot of users.

    I have two of those LCD displays and am trying to incorporate those into my system to display OBDII data. I have seen somewhere, a schematic of two of these LCD wired together. Has anyone got this to work?

    I thank for the replies above, this will give me a start to go from.
    Dual Lilliput's 70NP/C/T
    Syntax SV266AD KT266A
    AMD Athlon XP 2000
    Viking 256MB DDR
    D-Link Wireless 802.11B
    Seagate 120GB
    OrbitMicro 250W DC/DC converter
    SII Wireless Audio Link
    Digimoto OBD-II
    Earthmate GPS
    BU-303 USB GPS
    D-Link Bluetooth

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